In recent years, there has been a trend that a vehicle is equipped with an optical sensor such as a camera or a laser. It has been proposed that a compressed air generator for spraying compressed air is used to remove foreign matters such as water and dirt sticking to a lens surface of a lens of the optical sensor and that the foreign matters sticking to the lens surface is removed by spraying the compressed air from the compressed air generator onto the lens surface of the lens (refer to, for example, JP 2001-171491 A).
However, according to a technique disclosed in JP 2001-171491 A, the compressed air generator for spraying the compressed air is required. As a result, the cost and the size are increased.